Power supply system for a vehicle climate control unit

ABSTRACT

A truck includes an alternator having a direct current electrical power output. The truck also includes an inverter having an alternating current electrical power output, and a battery. The truck further includes a day cab forming an interior space and a climate control unit for conditioning the interior space of the day cab. The climate control unit has a conditioning capacity rating that is not greater than 7,000 British thermal units per hour (Btu/hr). The climate control unit is adapted to be powered by an alternating current electrical source. The climate control unit is powered by the alternator through the inverter when an engine of the truck engine is running and powered by the battery through the inverter when the engine is not running.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/784,336, filed Mar. 21, 2006, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to vehicle electrical powersupply systems, and more particularly to vehicle electrical power supplysystems that are adapted to supply power to vehicle-mounted heating,ventilation, and air conditioning (HVAC) systems when the vehicle'sengine is not running.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect, provided is a truck including analternator having a direct current electrical power output. The truckalso includes an inverter having an alternating current electrical poweroutput, and a battery. The truck further includes a day cab forming aninterior space and a climate control unit for conditioning the interiorspace of the day cab. The climate control unit has a conditioningcapacity rating that is not greater than 7,000 British thermal units perhour (Btu/hr). The climate control unit is adapted to be powered by analternating current electrical source. The climate control unit ispowered by the alternator through the inverter when an engine of thetruck is running and powered by the battery through the inverter whenthe engine is not running.

In accordance with another aspect, provided is a truck including analternator having a three-phase alternating current electrical poweroutput. A power converter converts the three-phase alternating currentelectrical power output from the alternator into a single-phasealternating current electrical power output and a direct currentelectrical power output. The truck further includes an inverter havingan alternating current electrical power output and a battery. A day cabon the truck forms an interior space. A climate control unit conditionsthe interior space of the day cab. The climate control unit has aconditioning capacity rating that is not greater than 10,000 Britishthermal units per hour (Btu/hr). The climate control unit is adapted tobe powered by an alternating current electrical source. The climatecontrol unit is powered by the alternator through the power converterwhen an engine of the truck is running and powered by the batterythrough the inverter when the engine is not running.

Further provided is a truck including an engine, an alternator driven bythe engine, and a starter motor for starting the engine. The truckfurther includes an inverter having an alternating current electricalpower output. A day cab on the truck forms an interior space. A climatecontrol unit conditions the interior space of the day cab. The climatecontrol unit is adapted to be powered by an alternating currentelectrical source. The climate control unit is powered by the alternatorthrough the inverter when the engine is running. A battery for supplyingelectrical energy to the starter motor also supplies electrical energyto the climate control unit through the inverter, to power the climatecontrol unit when the engine is not running.

Further provided is a method of modifying a truck. The method includesthe step of providing the truck. The truck includes an alternator havinga direct current electrical power output. The truck also includes abattery, and a day cab forming an interior space. A heating system heatsthe interior space of the day cab and an air conditioning system coolsthe interior space of the day cab. The method further includes the stepof installing an inverter on the truck. The inverter has an alternatingcurrent electrical power output. The method further includes the step ofinstalling an auxiliary HVAC unit on the truck. The auxiliary HVAC unithas a conditioning capacity rating that is not greater than 7,000British thermal units per hour (Btu/hr). The auxiliary HVAC unit isadapted to be powered by an alternating current electrical source. Theauxiliary HVAC unit is powered by the battery through the inverter whenan engine of the truck is not running.

Further provided is a method including the step of providing a truck.The truck includes an engine, an alternator driven by the engine, and astarter motor for starting the engine. The truck also includes aninverter having an alternating current electrical power output and abattery for supplying electrical energy to the starter motor. A day cabon the truck forms an interior space. A heating system heats theinterior space of the day cab and an air conditioner cools the interiorspace of the day cab. The method further includes the step of selectingan auxiliary climate control unit for conditioning the interior space ofthe day cab. The auxiliary climate control unit is adapted to be poweredby an alternating current electrical source. The method further includesthe step of installing the auxiliary climate control unit on the truckso that the climate control unit is powered by the alternator throughthe inverter when the engine is running and powered by the batterythrough the inverter when the engine is not running.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a truck having a day cab;

FIG. 2 is a schematic block diagram of a power supply system for avehicle-mounted HVAC unit; and

FIG. 3 is a schematic block diagram of a power supply system for avehicle-mounted HVAC unit; and

FIG. 4 is a schematic block diagram of a power supply system for avehicle-mounted HVAC unit.

DETAILED DESCRIPTION

Described herein is a vehicle electrical power supply system forsupplying power to a vehicle-mounted HVAC unit. The system is adapted tosupply power to the HVAC unit when the vehicle's engine is running ornot running. Accordingly, the power supply system allows the HVAC unitto be operated without idling the engine when the vehicle is parked.

As used herein, the terms “HVAC unit” and “climate control unit” refergenerally to a device for conditioning a space, which can include one ormore of the following functions: heating, cooling, ventilating, airhandling, humidifying, and dehumidifying. The terms “HVAC unit” and“climate control unit” are used interchangeably.

As used herein, the term “truck” refers to a self-propelled vehicle,having an internal combustion engine, for transporting various things(e.g., freight, livestock, etc.). The term “truck” includes a highwaytractor that is adapted to pull a semitrailer. An example truck 1 isshown in FIG. 1. The truck 1 includes a day cab 2. The day cab 2 is atruck cab having no driver sleeping compartment. A truck cab thatincludes a driver sleeping compartment is conventionally known as a“sleeper cab.” The day cab 2 is smaller than a sleeper cab because itlacks a sleeping compartment.

The day cab 2 forms an interior space. An HVAC system conditions theinterior space within the day cab 2. The HVAC system may be an auxiliaryHVAC unit that is auxiliary to the truck's main heating and airconditioning system. In an embodiment, the auxiliary HVAC unit is sizedspecifically to effectively condition the interior space within the daycab 2. That is, the heating, cooling, ventilating, air handling,humidifying and/or dehumidifying capacity of the day cab HVAC unit isdesigned specifically to condition a space within a day cab. Because aday cab HVAC unit is designed to condition a smaller space than asleeper cab HVAC unit, the day cab HVAC unit consumes less energy whenrunning.

In an example embodiment, the day cab HVAC unit has a conditioningcapacity rating, for example, a cooling capacity rating, that is notgreater than 10,000 British thermal units per hour (Btu/hr) or 2,930watts (W). In an example embodiment, the day cab HVAC unit has aconditioning capacity rating that is not greater than 7,000 Btu/hr or2,051 W. In an example embodiment, the day cab HVAC unit has aconditioning capacity rating that equals 10,000 Btu/hr or 2,930 W. In anexample embodiment, the day cab HVAC unit has a conditioning capacityrating that equals 7,000 Btu/hr or 2,051 W.

An HVAC unit for a day cab can be chosen based on the volume of theinterior space of the day cab and the conditioning capacity ratings ofavailable HVAC units. For example, the smallest effective HVAC unit(e.g., the unit having the smallest suitable conditioning capacityrating) can be chosen for a day cab so that a minimum amount of energyis required to operate the HVAC unit. Such an HVAC unit may beineffective to adequately condition the interior space of a sleeper cab,which is larger than the day cab.

A power system for a vehicle-mounted HVAC system is shown schematicallyin FIG. 2. The HVAC unit 3 can be a day cab HVAC unit, such as anauxiliary day cab HVAC unit. The HVAC unit 3 is shown as being suppliedby 120 Volts, alternating current (Vac). However, the HVAC unit could beadapted to be supplied by other and/or multiple voltages, such as 110Vac, 240 Vac, or 220 Vac, for example.

An inverter 4 supplies approximately 120 Vac to the HVAC unit 3. Theinverter 4 converts a direct current voltage (Vdc) to an ac voltage foruse by the HVAC unit 3. In an embodiment, the inverter 4 converts a dcvoltage of approximately 12 Vdc to 120 Vac for use by the HVAC unit 3.An inverter 4 could be chosen depending on the available dc inputvoltage and desired ac output voltage, and the invention discussedherein is not limited to a particular inverter 4 or particular ac or dcvoltage levels. The inverter 4 can be a modified sine wave inverter or apure sine wave inverter. Example inverters are rated at 1,800 Watt,2,000 Watt, 2,500 Watt, and 3000 Watt, respectively.

A battery 5 is connected to the inverter, to supply the dc input voltageto the inverter 4. In an embodiment, and as shown in FIG. 2, the battery5 is a starting battery for the engine and includes additional batteriesto form a battery bank. The primary purpose of a starting battery orstarting battery bank is to supply electrical energy to the truck'sstarter motor (not shown), for starting the truck's engine. However,when the truck's engine is not running, the starting battery can beconfigured supply electrical energy to various loads, such as a stereo,interior lights, the HVAC unit 3, etc. As shown in FIG. 2, the battery 5supplies electrical energy at approximately 12 Vdc to the inverter.

The inverter 4 includes a low voltage cut-out circuit to preventdischarging of the battery 5 to an undesirable level, for example to alevel at which the truck's engine cannot be started. An example cut-outvoltage level is 10.5 Vdc. When the battery voltage drops to or below10.5 Vdc, the inverter prevents further discharging of the batterythrough the inverter. In an embodiment, the inverter's cut-out circuitcan be remotely controlled via a control input at the inverter. Forexample, a control signal (e.g., a contact closure or a voltage signal)can be monitored by the inverter, and operations of the cut-out circuitcontrolled based on the state of the control signal. The control signalcan be provided by the HVAC unit 3, which operates intermittently toheat or cool the interior of the day cab 2, so that the cut-out circuitprevents discharging of the battery 5 whenever the HVAC unit 3 does notneed to operate.

Example batteries are deep-cycle absorbed glass mat type batteries andflooded lead-acid type batteries. Example batteries are rated at 75Ampere-hours (Ah) or less. In an embodiment, the batteries have anappropriate Ampere-hour rating for allowing operation of the HVAC unit 3for a duration of 3 hours or less while the truck's engine is notrunning. It is to be appreciated that batteries can be selected, basedon their Ampere-hour rating, for allowing operation of the HVAC unit 3for a duration exceeding 3 hours.

In an embodiment, the truck includes a battery box for holding thebattery 5 or battery bank. The battery box can be mounted to a framerail of the truck. In an embodiment, the inverter 4 is mounted withinthe battery box along with the battery 5.

An alternator, for example, a high capacity alternator 6, is driven bythe truck's engine and provides a dc charging voltage for the startingbattery bank 5 when the truck's engine is running. The truck's originalalternator can be replaced with a high capacity alternator 6, ifdesired. The alternator 6 can have a current rating that is greater than135 Amps, such as 185 Amps or 200 Amps, and the alternator can have anexternal regulator.

When the truck's engine is running, the HVAC unit 3 is supplied byapproximately 120 Vac from the inverter 4. The inverter 4 is supplied byapproximately 12 Vdc from the alternator 6 via the inverter's connectionto battery bank 5. The battery bank 5 is charged by the alternator 6while the engine is running.

When the truck's engine is not running, the HVAC unit 3 is supplied bythe inverter 4, which is supplied by the battery bank 5. However,because the truck's engine is not running, the battery bank 5 is notcharged by the alternator 6.

In an embodiment, the inverter 4 is adapted to receive an ac input froma power source external to the truck, such as a source of utility poweror an external generator, for example. This is shown in FIG. 2 as a 120Vac shore power source 7. Other shore power voltage levels could besupplied to the inverter 4, for example, 240 Vac. In an embodiment, theinverter 4 transforms a shore power voltage level to a voltage levelsuitable for use by the HVAC unit 3. When connected to the shore powersource 7, the inverter 4 supplies the HVAC unit 3 with electrical powerfrom the shore power source 7.

In an embodiment, the electrical power system includes an optional housebattery bank 8 in addition to the starting battery bank 5. The housebattery bank 8 is a bank of batteries that is dedicated to serving“house” loads when the truck's engine is not running. Example houseloads include the HVAC unit 3, stereo equipment, a coffee maker, etc.The house battery bank allows house loads to be operated when thetruck's engine is not running, without discharging the starting batterybank 5. Example house batteries are deep-cycle absorbed glass mat typebatteries and flooded lead-acid type batteries.

The house battery bank 8 is connected to the inverter 4. When thetruck's engine is not running, the HVAC unit 3 is supplied by the housebattery bank 8 through the inverter 4. Accordingly, the HVAC unit 3 doesnot discharge the starting battery bank 5 when the truck's engine is notrunning. A battery separator or isolator 9 interconnects the startingbattery bank 5 and the optional house battery bank 8 and allows thealternator to charge the house battery bank 8 when the engine isrunning, but prevents discharge of the starting battery bank 5 by theHVAC unit 3 when the engine is not running. The battery separator orisolator 9 can include a current-blocking device to prevent undesiredcurrent flow between the starting battery bank 5 and the house batterybank 8. For example, the battery separator or isolator 9 can includediodes to prevent undesired current flow. The battery separator orisolator 9 can also include controlled switching devices to preventundesired current flow, such as relays, solenoids, contactors,transistors, and the like. The battery separator or isolator 9 canprevent the flow of current from the starting battery bank to the housebattery bank 8.

In the embodiment of FIG. 3, the inverter 4 also functions as a batterycharger. When the inverter 4 is connected to shore power 5, the invertersupplies a charging voltage to the starting battery bank 5 and/or thehouse battery bank 8.

In the embodiment of FIG. 4, the alternator 6 produces three-phase, acpower. For example, the alternator produces approximately 42 Vac,three-phase power. The alternator 6 supplies three-phase ac power to apower converter 10. The power converter 10 converts three-phase ac powerfrom the alternator 6 to a dc voltage, for example, approximately 12Vdc, to charge the starting battery bank 5, and an ac voltage, forexample, approximately 120 Vac, to supply power to the HVAC unit 3. Anexample power converter 10 is sold under the tradename MOBILE POWERGENERATOR MPG-30. The power converter 10 supplies converted power fromthe alternator 6 to the starting battery bank 5 and HVAC unit 3 when thetruck's engine is running. When the truck's engine is not running, thepower converter 10 does not supply power to the starting battery bank 5or the HVAC unit 3.

The system of FIG. 4 includes a house battery bank 8 connected to thestarting battery bank 5 through a battery separator or isolator 9. Thehouse battery bank 8 is connected to an inverter 4, which is connectedto the HVAC unit 3. When the truck's engine is not running, the powerconverter 10 does not supply power to the HVAC unit 3. Instead, theinverter 4 supplies power to the HVAC unit 3 from the house battery bank8. The inverter 4 can be adapted to receive shore power 7 to supplypower to the HVAC unit 3. The inverter 4 can also function as a batterycharger as described above with respect to FIG. 3.

In an embodiment, the power converter 10 includes an integral inverter(not shown) for supplying ac power to the HVAC unit 3 from the startingbattery bank 5 and/or a house battery bank 8. The power converter's 8integral inverter allows the power converter 10 to supply ac power tothe HVAC unit 3 even when the truck's engine is not running.

It should be evident that this disclosure is by way of example and thatvarious changes may be made by adding, modifying or eliminating detailswithout departing from the fair scope of the teaching contained in thisdisclosure. The invention is therefore not limited to particular detailsof this disclosure except to the extent that the following claims arenecessarily so limited.

1. A truck, comprising: an alternator having a direct current electricalpower output; an inverter having an alternating current electrical poweroutput; a battery; a day cab forming an interior space; and a climatecontrol unit for conditioning the interior space of the day cab, whereinthe climate control unit has a conditioning capacity rating that is notgreater than 7,000 British thermal units per hour (Btu/hr), wherein theclimate control unit is adapted to be powered by an alternating currentelectrical source, and wherein the climate control unit is powered bythe alternator through the inverter when an engine of the truck isrunning and powered by the battery through the inverter when the engineis not running.
 2. A truck as set forth in claim 1, wherein the truck isa tractor adapted for pulling a semitrailer.
 3. A truck as set forth inclaim 1, wherein the battery is a house battery, and the truck furtherincludes: a starting battery; and a battery isolator for preventing aflow of current from the starting battery to the house battery.
 4. Atruck as set forth in claim 1, wherein the battery is an absorbed glassmat battery.
 5. A truck as set forth in claim 4, further comprising andadditional absorbed glass mat battery.
 6. A truck as set forth in claim5, wherein the battery and said additional battery have Ampere-hourratings that are not greater than 75 Ampere-hours.
 7. A truck as setforth in claim 5, wherein the conditioning capacity rating of theclimate control unit is a cooling capacity rating.
 8. A truck as setforth in claim 7, wherein the conditioning capacity rating equals 7,000Btu/hr.
 9. A truck, comprising: an alternator having a three-phasealternating current electrical power output; a power converter forconverting the three-phase alternating current electrical power outputfrom the alternator into a single-phase alternating current electricalpower output and a direct current electrical power output; an inverterhaving an alternating current electrical power output; a battery; a daycab forming an interior space; and a climate control unit forconditioning the interior space of the day cab, wherein the climatecontrol unit has a conditioning capacity rating that is not greater than10,000 British thermal units per hour (Btu/hr), wherein the climatecontrol unit is adapted to be powered by an alternating currentelectrical source, and wherein the climate control unit is powered bythe alternator through the power converter when an engine of the truckis running and powered by the battery through the inverter when theengine is not running.
 10. A truck as set forth in claim 9, wherein thebattery is an absorbed glass mat battery.
 11. A truck as set forth inclaim 9, wherein the conditioning capacity rating of the climate controlunit is a cooling capacity rating, and further wherein the conditioningcapacity rating is not greater than 7,000 Btu/hr.
 12. A truck as setforth in claim 9, wherein the battery is a house battery, and the truckfurther includes: a starting battery; and a battery isolator forpreventing a flow of current from the starting battery to the housebattery.
 13. A truck, comprising: an engine; an alternator driven by theengine; a starter motor for starting the engine; an inverter having analternating current electrical power output; a day cab forming aninterior space; a climate control unit for conditioning the interiorspace of the day cab, wherein the climate control unit is adapted to bepowered by an alternating current electrical source, and wherein theclimate control unit is powered by the alternator through the inverterwhen the engine is running; and a battery for supplying electricalenergy to the starter motor, wherein said battery supplies electricalenergy to the climate control unit through the inverter to power theclimate control unit when the engine is not running.
 14. A truck as setforth in claim 13, further comprising an additional battery, wherein thebattery and said additional battery form a battery bank for supplyingelectrical energy to the climate control unit through the inverter topower the climate control unit when the engine is not running.
 15. Atruck as set forth in claim 14, wherein the battery and said additionalbattery have Ampere-hour ratings that are not greater than 75Ampere-hours.
 16. A truck as set forth in claim 14, wherein the batteryand said additional battery are absorbed glass mat batteries.
 17. Atruck as set forth in claim 14, wherein the climate control unit has acooling capacity rating that is not greater than 7,000 British thermalunits per hour (Btu/hr).
 18. A method of modifying a truck, comprisingthe steps of: providing the truck, the truck including: an alternatorhaving a direct current electrical power output; a battery; a day cabforming an interior space; a heating system for heating the interiorspace of the day cab; and an air conditioning system for cooling theinterior space of the day cab; installing an inverter on the truck; theinverter having an alternating current electrical power output; andinstalling an auxiliary HVAC unit on the truck, wherein the auxiliaryHVAC unit has a conditioning capacity rating that is not greater than7,000 British thermal units per hour (Btu/hr); wherein the auxiliaryHVAC unit is adapted to be powered by an alternating current electricalsource; and wherein the auxiliary HVAC unit is powered by the batterythrough the inverter when an engine of the truck is not running.
 19. Amethod as set forth in claim 18, wherein the battery is a house battery,and the truck further includes: a starting battery; and a batteryisolator for preventing a flow of current from the starting battery tothe house battery.
 20. A method as set forth in claim 18, wherein thebattery has an Ampere-hour rating that is not greater than 75Ampere-hours.
 21. A method as set forth in claim 18, further comprisingthe step of: replacing the alternator with another alternator having acurrent rating that is greater than 135 Amps.
 22. A method as set forthin claim 21, further comprising the step of installing an absorbed glassmat battery on the truck.
 23. A method as set forth in claim 21, whereinthe conditioning capacity rating is a cooling capacity rating.
 24. Amethod as set forth in claim 23, wherein the conditioning capacityrating equals 7,000 Btu/hr.
 25. A method, comprising the steps of:providing a truck, the truck including: an engine; an alternator drivenby the engine; a starter motor for starting the engine; a battery forsupplying electrical energy to the starter motor; a day cab, wherein theday cab forms an interior space; a heating system for heating theinterior space of the day cab; and an air conditioner for cooling theinterior space of the day cab; providing an inverter having analternating current electrical power output; installing an auxiliaryclimate control unit on the truck, wherein the auxiliary climate controlunit is configured to condition the interior space of the day cab,wherein the auxiliary climate control unit is adapted to be powered byan alternating current electrical source, and wherein the auxiliaryclimate control unit is powered by the alternator through the inverterwhen the engine is running and powered by the battery through theinverter when the engine is not running.
 26. A method as set forth inclaim 25, further comprising the step of: replacing the alternator withanother alternator having a current rating that is greater than 135Amps.
 27. A method as set forth in claim 25, wherein the truck includesan additional battery, and the battery and said additional battery forma battery bank for powering the auxiliary climate control unit when theengine is not running.
 28. A method as set forth in claim 27, whereinthe battery and said additional battery have Ampere-hour ratings thatare not greater than 75 Ampere-hours, and further wherein the auxiliaryclimate control unit has a conditioning capacity rating that is notgreater than 7,000 British thermal units per hour (Btu/hr).